A. Field of the Invention
The present invention relates generally to the communications field, and, more particularly to an angular optical component retention and removal system for use in the communications field.
B. Description of the Related Art
Optical communication equipment is typically housed in bays, which include a rectangular frame having dimensions conforming to a particular standard, such as the Network Equipment Building Standard (NEBS). NEBS covers a large range of requirements including criteria for personnel safety, protection of property, and operational continuity. NEBS covers both physical requirements including: space planning, temperature, humidity, fire, earthquake, vibration, transportation, acoustical, air quality and illumination; and electrical criteria including: electrostatic discharge (ESD), electromagnetic interference (EMI), lightning and AC power fault, steady state power induction, corrosion, DC potential difference, electrical safety and bonding and grounding. The term “electrostatic discharge” or “ESD”, as used herein, refers to the rapid, spontaneous transfer of electrostatic charge induced by a high electrostatic field. Usually the charge flows through a spark (static discharge) between two bodies at different electrostatic potentials as they approach one another.
An optical communications equipment frame further typically has a plurality of shelves, each having one or more slots for accommodating circuit boards or cards that have optical and electrical components associated with a communication network mounted thereon. Such optical components include, but are not necessarily limited to optical module/components, connectors, lasers, photodetectors, optical amplifiers, switching elements, add/drop multiplexers etc. In addition, fiber optic cables typically connect to one or more component.
Furthermore, the recent increase in bandwidth requirements for telecommunications systems has resulted in more densely packed equipment and fiber optic cables than prior systems. Many carriers or other consumers of optical communications equipment have very limited floor space in which to place new equipment and fiber optic cables. For example, some carriers may only have a single open bay (or shelf) in which to place new equipment and fiber optic cables. If the communications equipment can be more densely packed, then a greater amount of equipment and fiber optic cables may be placed within the available space. The fiber optic cables housed within optical communications equipment are also exposed to damage when the doors to the equipment are closed due to the close fit between the doors and the fiber optic cables.
Electrical and electro-optical circuit packs (“circuit packs”), which are examples of optical modules/components, include a circuit board with components mounted thereon. In a typical interconnection scheme, a plurality of pins are provided through a backplane mounted at the far end of a shelf. Each circuit pack is inserted horizontally and/or vertically into the shelf (also known as a “subrack”) on guideways and through a faceplate so that the connector engages the appropriate pins for connection to that circuit pack when the circuit pack is in its final position. The circuit pack is usually inserted into the backplane using a lever, sometimes referred to as a latch, injector-ejector, or circuit pack ejector system.
Typically, circuit packs have front panels, which may have multiple connectors or other components that connect to other devices. The physical front panel size of the circuit pack limits the number of connectors that may be implemented. The circuit pack size (i.e., the front panel) is limited by the physical dimensions of the chassis.
Additionally, fiber or other copper cabling may extend from connectors fastened to a circuit pack front panel. Due to the cable bend radius limitations, a great deal of space in front of the circuit pack may be required. This space constraint may cause certain components to be unusable.
Presently, it is a problem in the field of communication cable installation to ensure the precise placement of the communication cable without the possibility of damage to the communication cable by the provision of tight bends, or inappropriate use of fasteners, or inadequate support to the communication cable. Such communication cables include conventional telephone cable having a plurality of copper conductors, coaxial cable, optical fiber, or the like. In all of these applications, the minimum radius of curvature of the communication cable is well defined, and bending the communication cable in a tighter bend can cause damage to the communication medium housed within the cable. The installer of communication cable is thus faced with the problem of routing the communication cable over surfaces, which typically include sharp bends, without over bending the communication cable, yet also securing the communication cable to these surfaces in a manner to ensure protection from damage.
This problem is further heightened when fiber optic cables (alternatively referred to as “optical fibers” or “fibers”) are used. Glass fibers used in such cables are easily damaged when bent too sharply and require a minimum bend radius to operate within required performance specifications. The minimum bend radius of a fiber optic cable depends upon a variety of factors, including the signal handled by the fiber optic cable, the style of the fiber optic cable, and equipment to which the fiber optic cable is connected. For example, some fiber optic cables used for internal routing have a minimum bend radius of 0.75 inches, and some fiber optic cables used for external routing have a minimum bend radius of 1.0 inches.
Damaged fiber optic cables may lead to a reduction in the signal transmission quality of the cables. Accordingly, fiber optic cables are evaluated to determine their minimum bend radius. As long as a fiber optic cable is bent at a radius that is equal to or greater than the minimum bend radius, there should be no reduction in the transmission quality of the cable. If a fiber optic cable is bent at a radius below the minimum bend radius determined for such cable, there is a potential for a reduction in signal transmission quality through the bend. The greater a fiber optic cable is bent beyond or below its minimum bend radius, the greater the potential for breaking the fiber(s) contained in the cable, and the shorter the life span of the cable.
If a network component requires maintenance or an upgrade, the circuit pack containing the component or a component module is typically removed from the shelf. However, since fiber optic cables are typically fragile, if the fiber optic cable is bent beyond the minimum bend radius during board or module removal, the fiber optic cable may break. Accordingly, removal and insertion of component boards or modules can be difficult and inconvenient.
FIG. 1 shows a conventional arrangement 100 for mounting optical module/components 102 and other optical components 104 horizontally in the shelf of an optical communications equipment frame (not shown). Arrangement 100 includes a faceplate 106 attached to a “mother” or main printed circuit board (“PCB”) 108 and through which optical module/components 102 and optical components 104 may be provided. A handle 110 and a releasable handle 112 may connect to faceplate 106 for releasably attaching faceplate 106 and main PCB 108 to the shelf. Screws 114 may also be provided through faceplate 106 for releasably connecting faceplate 106 and main PCB 108 to the shelf.
Optical module/components 102 releasably connect through openings in faceplate 106 with spring retainers 116. Spring retainers 116 releasably engage faceplate 106 when optical module/components 102 are pushed into the openings of faceplate 106. Each optical module/component 102 may be removed from faceplate 106 by forcing spring retainers 116 inward toward optical module/component 102, and by pulling optical module/component 102 away from faceplate 106. This is a cumbersome process since two spring retainers 116 need to be manipulated while each optical module/component 102 is manually pulled away from faceplate 106.
As further shown in FIG. 1, optical module/components 102 and optical components 104 are aligned horizontally in faceplate 106. With this configuration, the fiber optic cables or optical cables 118 emanating from optical module/components 102 and optical components 104 also extend horizontally, requiring, for example, a distance A of empty space in front of faceplate 106 for accommodation of cables 118 without bending cables 118 beyond their minimum bend radii. If proper spacing is not provided between faceplate 106 and the optical communications cabinet door, then fiber optic cables 118 may be bent beyond their minimum bend radii, potentially damaging cables 118 and communication link provided thereby.
Thus, there is a need in the art for an optical component retention and removal system that overcomes the limitations and problems of the related art.